Most of the people most likely to buy from you already know you. They've visited your website, bought from you before, or watched one of your videos. Custom audiences are how you reach them on Facebook and Instagram, and just as usefully, how you stop paying to reach them when you don't need to.
The short answer: a Facebook custom audience is a group of people who have already interacted with your business, built from your website visitors, your customer list, your app users, or people who've engaged with you on Facebook or Instagram. You can show ads to that group, exclude it from a campaign, or use it as the starting point for a lookalike audience.
What is a Facebook custom audience?
A custom audience is a list Meta builds from information you already have, or from activity it can see, and matches to people's Facebook and Instagram accounts. Unlike interest or demographic targeting, it isn't a guess about who might care. It's a group of people who already have a relationship with your business.
You create them in Meta Ads Manager under Audiences, and they work across Facebook, Instagram, Messenger, and Meta's Audience Network. Meta has renamed a lot of things since Facebook became Meta, but "custom audiences" is still what they're called.
The five types of custom audiences
| Type | Built from | What you need | Best for |
|---|---|---|---|
| Website | People who visited your site or took actions on it | The Meta Pixel, ideally with the Conversions API | Retargeting visitors, cart abandoners, and past buyers |
| Customer list | Emails and phone numbers you upload or sync | A list you have permission to use | Excluding customers, win-back, and lookalikes |
| Engagement | People who interacted with you on Facebook or Instagram | A Facebook Page, Instagram account, videos, or lead forms | Warming up people who know you but haven't visited your site |
| App activity | People who opened or took actions in your app | Meta's SDK and app events set up | Re-engaging app users and driving in-app purchases |
| Catalog | People who viewed or added specific products | A product catalog connected to your Pixel | Catalog ads showing people the products they looked at |
Website custom audiences
These are built from activity on your own site, tracked by the Meta Pixel. You can include everyone who visited, people who viewed specific pages, or people who took actions like adding to cart or purchasing, over a window of up to 180 days.
Since Apple and the major browsers tightened tracking, the Pixel alone misses a share of visitors, so website audiences are smaller than they used to be. Setting up the Conversions API alongside the Pixel sends the same events from your server and recovers much of that loss. On Shopify and most major platforms, it's a built-in integration.
Customer list custom audiences
Upload a list of customer emails or phone numbers, or sync one from your email platform or CRM, and Meta matches it to accounts. The data is hashed before it's matched, so Meta doesn't receive the list in readable form. Expect only part of the list to match, since people often sign up with a different email from the one on their Facebook account. Adding phone numbers, names, and locations improves the match.
Two rules: only upload people who've agreed to hear from you, and keep the list current. A customer list from a year ago will keep excluding people who've since lapsed and miss everyone who's bought since. A direct integration that syncs automatically is worth setting up.
Engagement custom audiences
These are built from activity on Meta's own apps, so they don't depend on your website tracking at all. Sources include:
- People who watched a set amount of one of your videos
- People who engaged with your Facebook Page or Instagram account
- People who opened or submitted one of your lead forms
- People who responded to one of your events
- People who opened an Instant Experience
Video viewers are especially useful. People who watched most of a video are a clear signal of interest, and building that audience costs far less than driving the same people to your website.
App activity and catalog audiences
If you have an app, Meta's SDK lets you build audiences from what people do in it, like opening it, reaching a level, or making a purchase. If you sell products online, catalog audiences group people by the products they viewed or added to cart, and power the catalog ads that show them those exact items.
How to create a custom audience
- In Meta Ads Manager, open Audiences.
- Click Create audience and choose Custom audience.
- Pick a source: website, customer list, app activity, catalog, or one of Meta's engagement sources.
- Set the rules, such as which pages or events to include and how many days back to look.
- Give it a clear name that says what's in it and the time window, like "Website | Add to cart | 30 days." Our guide to Meta Ads naming conventions covers how.
Meta needs a minimum number of matched people before it will deliver ads to an audience, and small audiences are expensive to reach and wear out quickly. If an audience is only a few hundred people, widen the time window or combine it with a related one.
Six ways to use custom audiences
- Retarget by how recently people engaged. Someone who added to cart yesterday needs a different ad from someone who visited three months ago. Split website audiences by time window and adjust the message and budget to match.
- Exclude people you don't need to pay for. Excluding recent purchasers from campaigns meant to find new customers is one of the simplest ways to stop wasting budget, and it keeps your new customer acquisition cost honest.
- Seed lookalike audiences. A lookalike finds people similar to a custom audience. The better the seed, the better the lookalike, so your best customers usually make a stronger starting point than all visitors.
- Cross-sell and win back. Show past buyers a complementary product, or target customers who haven't purchased in a while with a reason to come back.
- Move leads toward a sale. People who downloaded a guide or watched a demo video can see ads with case studies, pricing, or an offer.
- Tell Meta who your existing customers are. Meta's automated sales campaigns and reporting can use your customer lists to separate new customers from returning ones, which makes both the targeting and the results easier to read.
How custom audiences fit with broad targeting
Meta increasingly finds customers on its own, using broad targeting and your creative rather than audiences you define. In that setup, a custom audience you add to a campaign is often treated as a suggestion. Meta starts there but may show your ads beyond it.
That doesn't make custom audiences less useful. It changes what they're for. Exclusions, retargeting windows, lookalike seeds, and telling new customers from existing ones are all still jobs only custom audiences can do. They've gone from being the whole targeting strategy to being the part that keeps it accurate.
Common mistakes to avoid
- Audiences that are too small. A 200-person retargeting audience will see the same ad over and over. Combine audiences or lengthen the window.
- Overlapping audiences. If "visited in the last 30 days" and "visited in the last 7 days" run in separate ad sets without excluding each other, they compete for the same people.
- Stale customer lists. A one-time upload goes out of date quickly. Sync it automatically or refresh it monthly.
- Relying on the Pixel alone. Without the Conversions API, website audiences shrink and retargeting misses people.
- Skipping consent. Only upload people who have agreed to hear from you. Meta's terms require it, and so do privacy laws in many places.
Custom audiences have gone from the whole targeting strategy to the part that keeps it accurate.
The bottom line: set up the Pixel and Conversions API, keep a synced customer list, and build a few well-named audiences by source and time window. Then use them to retarget, to exclude, and to seed lookalikes. If you'd like a hand setting them up or auditing the ones you have, we're happy to help.